There is no doubt that the events aboard an airliner heading for Detroit on Christmas Day sent a collective chill down the spines of travelers everywhere. The attempted attack on that plane could easily have ended tragically, and we're all grateful it didn't. In the aftermath, it's necessary for political leaders to find out what went wrong and what more can be done to protect our nation against terrorism.

But while it's important to react quickly, it's also important to react wisely and to adopt procedures that will be both truly effective and the least invasive to Americans' privacy.

After the 9/11 attacks, many policies — from the overly broad Patriot Act to indefinite detention to misguided airline security measures — that, unfortunately, succeeded in neither increasing our safety nor honoring our values were quickly adopted. We should learn from that experience and in circumstances like this one insist on security measures that are actually effective rather than ones that just make us feel better.

For example, much talk this week has centered on airport security measures such as full-body-scanning technology, with speculation that such machines might have detected the hidden bomb material. But the effectiveness of such technology is far from clear. Experts have suggested that plastic explosives can be hidden from body scanners, and terrorists have proved adept in evading the post-9/11 security measures we've implemented. Al-Qaida has already launched attacks with explosives hidden in body cavities, which these machines cannot detect.

Other talk this week has been about terrorist watch lists, with some arguing that there should be more people, not fewer, on the lists. But to be effective, no-fly lists should be focused on true terrorists who pose a genuine threat to flight safety. Right now, the lists are bloated and unmanageable, keeping innocent travelers off their flights (remember Cat Stevens and Nelson Mandela?). This distracts from true terrorist threats while, as the recent event demonstrates, failing to identify true threats.

Instead, the government must find a better way to stop terrorist attacks than intrusive body scanners of questionable value and ineffective watch lists. Hindsight is always 20/20, but in several recent cases there appears to have been evidence that should have triggered more timely and detailed investigations, but that evidence was either lost in the vast seas of information now being collected under loosened surveillance laws, or was simply not shared effectively or acted upon properly.

We should invest our security resources in investigations based upon reasonable suspicion of wrongdoing so we can more effectively identify and stop attackers before they get to any airport. We must also hold our law enforcement and intelligence agencies accountable to ensure that the vast powers they've been given over the past nine years are being used effectively and responsibly.

Profiling and electronically strip searching the innocent doesn't help find terrorists, it only wastes security resources. While we must work fervently to provide the best security possible, we must recognize that our constitutional freedoms are what we are ultimately trying to protect.

Americans can't afford to be complacent about giving up civil liberties, especially to ineffective policies that don't make us safer. Providing for security and liberty is not a zero-sum game. In America we should strive to be both safe and free.